Composite material with controlled elasticity

ABSTRACT

A controlled elastic composite material which is produced by forming a flexible elastomer layer or layers on one or both surfaces of at least one member selected from the group consisting of (a) a longitudinally monoaxially oriented reticular web, (b) a transversally monoaxially oriented reticular web, (c) a woven or non-woven fabric composed of monoaxially oriented tapes, and (d) a stretched long fiber web in which long fibers are aligned almost in one direction.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a composite material with controlledelasticity. More particularly, the invention relates to a compositematerial which is made by forming a flexible elastomer layer or layerson a specific monoaxially oriented material so as to exhibit controlledelasticity. The composite materials of this kind with the controlledelasticity are widely used for producing disposable diapers, clothing,gloves, shoe covers, caps, adhesive plasters, bandages, and tapes forwinding round joint tubes of electric wires and pipings.

(2) Description of the Prior Art

There has been proposed various kinds of sheet materials havingflexibility, elasticity or resilience as those for producing sportswearfor skiing, motor sports and marine sports, clothes for working andsurgical operation, working gloves in food works, gathers of caps andhats, bracelets, suspenders, belts, poultices, diapers and so forth.

For example, the method for producing elastic composite material bycombining an elastic and flexible material and a non-elastic materialfor forming pleats is disclosed in Japanese Laid-Open Patent PublicationNos. Sho 59-59901, Sho 62-33889, Hei 6-31833, Hei 6-31869, and Hei6-47808. A method for producing embossed elastic fabric made of elasticfabric and non-elastic sheet is disclosed in Japanese Laid-Open PatentPublication No. Sho 63-92433. Methods for laminating non-woven fabricand rubber-like elastic threads are disclosed in Japanese Laid-OpenPatent Publication Nos. Sho 61-289163 and Hei 3-213543. Methods for alaminating polyurethane film and polyurethane nonwoven fabric aredisclosed in Japanese Laid-Open Patent Publication Nos. Sho 62-121045and Sho 62-162538. A method for producing elastic laminates of specificthermoplastic rubber layers and non-woven fabric is disclosed inJapanese Laid-Open Patent Publication No. Hei 3-158236.

In the fixtures for the waist parts of disposable diapers, clothes forworking and surgical operation, caps for food works, garbage collectingand IC manufacturing works, fixtures for gloves and shoe covers,adhesive plasters, and bandages, it is required that the materialsexhibit controlled proper flexibility and elasticity in one direction orin various directions as well as mechanical strength. However, theelastic and flexible composite materials disclosed in the foregoingreferences can neither meet these requirements nor be produced easily atlow cost.

BRIEF SUMMARY OF THE INVENTION

The present inventors have carried out intensive investigations to solvethe above-mentioned problems.

As a result, it has been found out that an elastic composite materialexhibiting mono-axially or multi-axially controlled proper flexibilityand elasticity as well as mechanical strength can be produced bycombining a specific mono-axially oriented material made ofthermoplastic resin with an a flexible elastomer layer. In consequence,the present invention has been accomplished.

It is, therefore, a first object of the present invention to provide acontrolled elastic composite material which is produced by forming aflexible elastomer layer or layers on one or both surfaces of at leastone member selected from the group consisting of the followingmonoaxially oriented materials (a), (b), (c) and (d) which are made ofthermoplastic resin:

(a) a longitudinally monoaxially oriented reticular web,

(b) a transversally monoaxially oriented reticular web,

(c) a woven or non-woven fabric composed of mono-axially oriented tapes,and

(d) a stretched long fiber web in which long fibers, includingcontinuous fibers, are aligned almost in one direction.

A second object of the present invention is to provide the controlledelastic composite material which is made by forming a flexible elastomerlayer or layers on one or both surfaces of the composite material, whichcomposite material is made by laminating crosswise at least one kind ofabove-mentioned monoaxially oriented materials of (a), (b), (c) and (d)at an angle of 10° to 80°.

In the present invention, because the controlled elastic compositematerial is made by forming a flexible elastomer layer or layers on oneor both surfaces of the composite material, which composite material ismade by laminating crosswise specific monoaxially oriented reticular webor stretched long fiber web at an angle of 10° to 80°, the product ofelastic composite material exhibits proper controlled flexibility andelasticity in one axial direction or in both longitudinal andtransversal directions. In addition, it has very high mechanicalstrength. Especially, when the stretched long fiber web is used, theproduct has large strength as well as excellent feeling and drape.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome more apparent in the following description with reference toseveral embodiments and accompanying drawings, in which:

FIG. 1A is an enlarged perspective view of a part of a longitudinallymonoaxially oriented reticular web (a),

FIG. 1B is a schematic illustration of the laminate layers of alongitudinally monoaxially oriented reticular web (a),

FIG. 2 is a schematic illustration of a process for producing thelongitudinally monoaxially oriented reticular web (a) of the presentinvention,

FIG. 3A is an enlarged perspective view of a part of a transversallymonoaxially oriented reticular web (b),

FIG. 3B is a schematic illustration of the laminate layers of atransversely monoaxially oriented reticular web (b),

FIG. 4 is a schematic illustration of a process for producing thetransversally monoaxially oriented reticular web (b),

FIG. 5 is an enlarged perspective view of a monoaxially oriented tape(c) of an embodiment of the present invention,

FIG. 6 is a microphotograph of the stretched long fiber web (d),

FIG. 7 is schematic partial perspective view of a transversallystretching device, and

FIG. 8 is schematic partial perspective view of a near-roll stretchingdevice.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in more detail.

FIG. 1A is an enlarged perspective view of a longitudinally monoaxiallyoriented reticular web (a).

The longitudinally monoaxially oriented reticular web 1 shown in FIG. 1Ais prepared by laminating second thermoplastic resin layers 3 to boththe surfaces of a first thermoplastic resin layer 2 to obtain amulti-layer film, as depicted in FIG. 1B, and it is subjected toorientation treatment of stretching and/or rolling. The oriented film isthen treated in a fibrillation process in which it is subjected tocross-stitch pattern splitting in the longitudinal direction. In thisdrawing, the reticular web 1 consists of stem fibers 4 and branch fibers5.

As shown in FIG. 2, the longitudinally monoaxially oriented reticularweb (a) is prepared through the steps of:

(1) a film fabrication step for preparing a multi-layer film,

(2) an orientation step for orienting the multi-layer film,

(3) a fibrillation step for splitting the oriented multi-layer film in adirection parallel to the orientation axis, and

(4) a winding step for winding the fibrillated film.

The each of the above steps will be described in more detail.

In the film fabricating step for producing the multi-layer film of thepresent invention in FIG. 2, a first thermoplastic resin is fed to amain extruder 11 and a second thermoplastic resin is fed to twosubextruders 12, 12, respectively. The multi-layer film is then formed,in which the film comprises an inner core layer (an orienting layer)made of the first thermoplastic resin fed from the main extruder 11 andouter layers of the second thermoplastic resin fed from the twosubextruders 12, 12. In the present invention, the film is fabricatedthrough a multi-layer circular die 13 with the three extruders andthrough the water-cooling down-blow extrusion process 14. However, themethod for preparing the multi-layer film is not limited to themulti-layer blown film extrusion method or the multi-layer T-die method.In various methods, the water-cooling blown film extrusion method ispreferable because it has an advantage that a rather thick film can becooled rapidly without losing the transparency of the film.

In the orientation step of the present invention, the tubularmulti-layer film prepared in the above step is flattened and cut intotwo sheets of films F, F', and these films are then oriented at anorientation ratio of 1.1 to 15, preferably 5 to 12, more preferably 6 to10, relative to the initial size. In the orientation step, the twosheets of films are heated to a predetermined temperature by an oven 15which is equipped with infrared heaters or hot-air fans.

The above-mentioned orientation temperature is lower than the meltingpoint of the first thermoplastic resin of the core layer, and it isusually in the range of 20° to 160° C., preferably 60° to 150° C., andmore preferably 90° to 140° C. The orientation is preferably carried outstep by step in a multi-stage apparatus.

For carrying out the orientation, there are a roll stretching method(free monoaxially stretching method), hot plate stretching method,cylinder stretching method, hot air stretching method and rollingmethod. The orientation method as referred to in the present inventionincludes these ordinary stretching method as well as the rolling method.Any one of the above-mentioned orientation methods can be used, however,the rolling method, especially the free monoaxially stretching method ispreferable.

The rolling method referred to in the present invention is a method inwhich a thermoplastic resin film is passed between a set of two hotrolls having a gap smaller than the thickness of the film, and the filmis pressed through the gap at a temperature lower than the melting point(softening point) of the resin film, thereby stretching the film as muchas the ratio of decrease in thickness.

The free monoaxially stretching method as herein referred to means amethod in which the stretching distance (the distance between alow-speed roll and a high-speed roll) is made sufficiently larger thanthe width of the film, and the film is stretched freely with allowingthe decrease of the width of film.

In the fibrillation step of the present invention, the multi-layer filmwhich has been oriented in the above step is brought into slidingcontact with a fibrillator (rotary blades) 16 which is rotated at a highspeed so as to fibrillate the films F, F'.

As the above-mentioned fibrillation method, there can be used any one ofmethods to make numerous cuts or slits in the monoaxially orientedmulti-layer film such as mechanical methods to beat, twist, scrape, rub,or brush the monoaxially oriented films or other methods using air jet,ultrasonic wave or laser beams.

Among these fibrillation methods, the rotary mechanical method ispreferable. In the rotary mechanical method, fibrillators of varioustypes such as a tapping screw type splitter, a file-like coarse surfacesplitter and a needle roll splitter can be used. For example, apreferable tapping screw type splitter is usually in the shape ofpentagonal prism or a hexagonal prism and 10 to 40 threads, preferably15 to 35 threads per inch. The preferable file-like coarse surfacesplitter is disclosed in Japanese Utility Model Publication No. Sho51-38980. The file-like coarse surface splitter is a rod whosecross-section is circular and has a surface like a round file for ironworks or a similar ones. On the surface of the rod, two spiral groovesare formed at a regular pitch. Typical examples of such file-like coarsesurface splitter are also disclosed in U.S. Pat. Nos. 3,662,935 and3,693,851.

The method for making the above-mentioned reticular web is not limitedparticularly. However, a preferable method comprises arranging asplitter between nip rolls, moving the monoaxially oriented multi-layerfilm along the splitter under tension, and bringing the film intosliding contact with the splitter which is rotated at a high speed, soas to fibrillate the film into a reticular film.

The moving velocity of the film is usually in the range of 1 to 1000m/min, preferably 10 to 500 m/min. Furthermore, the rotational speed(peripheral velocity) of the splitter can be suitably selected inconsideration of the physical properties and the moving velocity of thefilm, and the desired properties of the reticular film to be obtained.The rotational speed is usually in the range of 10 to 3000 m/min, andpreferably 50 to 1000 m/min.

The longitudinally monoaxially oriented reticular web (a) which has beenthus fibrillated by splitting is, if desired, spread in the direction ofits width, subjected to a heat roll 17 in the heat treatment step, woundup to a predetermined length on a winding roll 18 in the winding step,and the obtained roll is supplied as a final product.

The transversally oriented reticular web (b) according to the presentinvention can be a single-layer film, however, it is preferably the onewhich is formed by the lamination of a second thermoplastic resin filmor films on one or both surfaces of a first thermoplastic film, in whichthe melting point of the second thermoplastic film is lower than that ofthe first thermoplastic film. The laminated multi-layer film is thenfibrillated in parallel to the direction to be oriented (transversal)using a slitter or other fibrillating device in a cross-stitch pattern,which is followed by transversal stretching or rolling, heat treatmentand width spreading.

FIG. 3A shows an enlarged partial perspective view of a transversallymonoaxially oriented reticular web (b) of an embodiment of the presentinvention.

FIG. 3B illustrates the transversally monoaxially oriented reticular web6 to be a multi-layer film which is composed of a first thermoplasticresin layer 2 and second thermoplastic resin layers 3 which are appliedto both surfaces of the first thermoplastic resin layer 2.

FIG. 4 is a schematic illustration of an embodiment of the manufacturingprocess for producing the transversally monoaxially oriented reticularfilm (b) in accordance with the present invention.

The transversally monoaxially oriented reticular web b is made throughthe steps of:

(1) a film fabrication step for preparing a multi-layer film,

(2) a slitting step for fibrillating the multi-layer film,

(3) an orienting step for stretching the multi-layer film in thedirection parallel to the direction of slitting, and

(4) a winding step for winding the slit and oriented film.

The respective steps will be described.

In FIG. 4, in the film fabrication step for preparing the multi-layerfilm, a first thermoplastic resin is fed to a main extruder 21 and asecond thermoplastic resin is fed to a subextruder 22. The blown filmextrusion is then carried out to form a tubular film. This tubular filmis composed of two layers of an inner layer of the first thermoplasticresin from the main extruder 21 and an outer layer of the secondthermoplastic resin from the subextruder 22. In the present invention,the film can be formed through a multi-layer circular die 23 with theuse of the two extruders through down-blow water-cooling blown filmextrusion 24. The method for preparing the multi-layer film is notparticularly limited to this multi-layer blown film extrusion method ora multi-layer T-die film method as stated in the description on thelongitudinally monoaxially oriented reticular film (a). Among these filmforming methods, the water-cooling blown film extrusion method ispreferable because the method has an advantage that a transparent filmcan be produced by rapidly cooling a thick film. In addition, accordingto the present invention, the obtained film is slightly oriented bypressing it between rolls so as to bond the inner layers of theflattened tube, thereby obtaining a three-layer film composed of thelayers of second thermoplastic resin/first thermoplastic resin/secondthermoplastic resin!. In this method, the two extruders are used inplace of the three extruders for preparing the foregoing longitudinallymonoaxially oriented reticular web, which method leads to a largeeconomical advantages.

In the slitting step of the present invention, the tubular multi-layerfilm is flattened by pinching, slightly oriented by rolling into the athree-layer film of second thermoplastic resin/first thermoplasticresin/second thermoplastic resin!. In the transversally slitting step25, the film is then transversally slit at right angles to its runningdirection (TD) to form numerous slits in cross-stitch pattern in thefilm. The above-mentioned slitting is attained by using sharp bladessuch as razor blades or high-speed rotary cutting blades, a scorecutter, a shear cutter or a heat cutter. Among them, the slitting withthe heat cutter is most preferable.

Some examples of the heat cutter are disclosed in Japanese PatentPublication No. Sho 61-11757, U.S. Pat. No. 4,489,630, and U.S. Pat. No.2,728,950. The slitting with a heat cutter produces an effect that theedges of slits in the slightly oriented film by the rolling in theprevious step, are rounded and thickened by partial fusion. Owing tothis effect, the slits can be prevented from tearing and over running ofslits in the succeeding transversally orienting step.

In the orienting step of the present invention, the slit film istransversally (TD) oriented in the section 26. The orientation can becarried out by a tenter method or a pulley method, in which the pulleymethod is preferable because a small-sized device can be usedeconomically. This pulley method is disclosed in British Patent No.849436 and Japanese Patent Publication No. Sho 57-30368. The conditionsfor the orienting are the same as those in the above-mentionedorientation step for the longitudinally monoaxially oriented reticularweb.

The transversally monoaxially oriented reticular web (b) is thensubjected to heat treatment 27 and wound in the winding step 28.

The above-mentioned monoaxially oriented multi-layer tape (c) for thewoven fabric or non-woven fabric is produced by monoaxially orienting amulti-layer film of the first thermoplastic resin layer and secondthermoplastic resin layer which is prepared by a multi-layer extrusionsuch as blown film extrusion or multi-layer T-die film method. Themulti-layer film is monoaxially oriented at a orienting ratio of 1.1 to15, preferably 3 to 10 before and/or after the cutting. The cut tapesare formed into woven fabric or non-woven fabric by putting themtogether crosswise at an angle of 10° to 80°. In some case, it ispossible that the monoaxially oriented tapes are aligned in parallel andtemporarily stuck together and they are laminated crosswise with anelastomer sheet or sandwiches with elastomer sheets to obtain theelastic composite material of the present invention.

FIG. 5 is an enlarged perspective view of an embodiment of a monoaxiallyoriented multi-layer tape (c). In this drawing, a monoaxially orientedmulti-layer tape 7 comprises a first thermoplastic resin layer 2 andsecond thermoplastic resin layers 3, 3.

The ratio of thicknesses of the first thermoplastic resin layer and thesecond thermoplastic resin layer is not especially limited. It is,however, preferable that the thickness of the second thermoplastic resinlayer is not more than 50% to the total thickness, preferably less than40% in order to maintain the mechanical strength of the multi-layertape. The thickness of the multi-layer film or the first thermoplasticresin layer after the orienting is preferably about 20 to 100 μm. Thethickness of the second thermoplastic resin layer is 3 μm or more inview of several properties such as the adhesive strength in thermaladhesion. The thickness is, however, generally in the range of 3 to 60μm, preferably 5 to 40 μm.

Examples of the foregoing first thermoplastic resins are homopolymers ofα-olefins such as high density and medium density polyethylenes,polypropylene, polybutene-1, poly-4-methylpentene-1, and polyhexene-1;copolymers of α-olefins such as ethylene-propylene copolymer; and otherpolymers of polyamide, polyester, liquid-crystalline polyester,polycarbonate and polyvinyl alcohol. So long as it is a crystallineresin which excels in stretching property, the resin is not especiallylimited.

Examples of the foregoing second thermoplastic resins which have meltingpoints lower than that of the first thermoplastic resin are non-polarpolyethylenes such as high density, medium density and low densitypolyethylenes, linear low density polyethylene, and ultra low densitypolyethylene; ethylene-vinyl ester copolymers such as ethylene-vinylacetate copolymer; ethylene-acrylic ester copolymer such asethylene-ethylacrylate copolymer; ethylene-methacrylic ester copolymersuch as ethylene-ethylmethacrylate copolymer; copolymers of ethylene andα, β-unsaturated carboxylic acid such as the copolymer of ethylene andmaleic acid or its ester; propylene polymers such as polypropylene andethylene-propylene copolymer; modified-polyolefin which is modified withunsaturated carboxylic acid; and mixture of the above materials.

It is desirable that the difference of melting points of the above firstthermoplastic resin and the second thermoplastic resin is not lower than5° C. in order to facilitate the production with maintaining theorienting characteristics of the first thermoplastic resin and crosswiselamination of monoaxially oriented materials. More preferabletemperature difference is 10° to 50° C.

The stretched long fiber web (d) of the present invention is made byspinning long fibers with a thermoplastic resin, monoaxially stretchingthe web so as to align the long fibers in one direction. The ratio ofstretching of the long fiber web is in the range of 5 to 20 and theaverage degree of fineness of the fiber is in the range of 0.01 to 10denier.

The stretched long fiber web (d) of the present invention is composed ofstretched long fibers most of which fibers are regularly aligned in onedirection in the plane of the web. More particularly, the following longfiber webs are prepared:

(1) A long fiber web which is made by spinning a thermoplastic resininto continuous fibers and by hot air circularly moving or by vibration.The web is composed of spun filaments which can be stretched in thestretching ratio of 2 or higher.

(2) A long fiber web which is made by spinning a thermoplastic resin andby stretching, untangling, accumulating and sheet formation.

(3) A long fiber web which is made by subjecting the bundles of longfibers of a thermoplastic resin to stretching, crimping, untangling, andwidth spreading.

(4) A web which is made by expanding flashingly of a thermoplastic resinwith the special solvent and accumulating and sheet formation.

(5) A melt blown non-woven fabric which is formed by spraying athermoplastic resin together with high pressure and high temperature,and then by untangling and aligning.

The long fiber web is then stretched longitudinally and/or transversallyby rolling, near-roll stretching, tenter stretching, pulley stretchingor hot plate stretching, and if necessary, it is further subjected toaligning treatment roughly in one direction to obtain the stretched longfiber web (d) of the present invention.

FIG. 6 is a microphotograph (magnification: 17) of the stretched longfiber web (d) in which stretched long fibers are aligned almost in onedirection.

Particular methods for producing the above stretched long fiber web (d)are disclosed in Japanese Patent Publication No. Hei 3-36948 andJapanese Laid-Open Patent Publication Nos. Hei 2-242960 and Hei2-269859.

In one example, melting filaments which are extruded from apertures ofspinning head are scattered by circularly moving air and they areaccumulated on a conveyor belt to obtain a long fiber random non-wovenfabric having longitudinal or transversal alignment of fibers. Using thetransversally stretching device as shown in FIG. 7, a long fiber web inwhich fibers are previously aligned transversally is transversallystretched under hot air blowing.

The transversally aligned web is stretched in the direction oftransverse with a transversally stretching device. An example of thetransversally stretching device is shown in FIG. 7, in which a web 31composed of transversally aligned long fibers is introduced into aheating chamber 32 and it is stretched by the pulley-type transversallystretching device. In this device, both the selvages of web 31 arepinched with a pair or stretching pulleys 33a, 33b and circulating belts34a, 34b which run along the circumference of the pulleys 33a, 33b.Because the distance between the pulleys are enlarged in the downstreamside, the web 31 is stretched transversally.

It is possible to control the ratio of stretching by changing the angleof opening between both the pulleys, however, if the ratio of stretchingis very large, the stretching may be done in multi-stage treatment.

As the heating medium in the heating chamber 32, hot water, hot air orsteam may be used.

FIG. 8 is a schematic partial perspective view of a near-roll stretchingdevice. A long fiber web 36 in which fibers are previously aligned inlongitudinal direction is passed around the rolls 37, 38, the rotationalspeeds of which rolls are different from each other. The rotationalspeed of the upstream roll 37 is smaller than that of the downstreamroll 38, thereby attaining the stretching of the web 36 withoutexcessively reducing the width of web 36. In the present invention, thecombination of the above devices can also be employed.

The ratio of stretching of the above stretched long fiber web is in therange of 5 to 20, preferably 8 to 12. The average degree of fineness ofthe long fiber is in the range of 0.01 to 10 denier, preferably 0.01 to5 denier. More particularly, the 0.01 to 10 denier fibers which are madeby rolling or stretching spun filaments of 0.2 to 50 denier, aredesirable.

The unit weight of the above long fiber web is selected from the rangeof 5 to 100 g/m², which differs in view of uses and purposes.

A stretched long fiber web according to the present invention ispreferably a conjugated fiber material which is made of a firstthermoplastic resin having a relatively higher melting point and asecond thermoplastic resin having a melting point lower than that of thefirst thermoplastic resin. The conjugated fiber is exemplified by a longfiber which is composed of a core material made of the firstthermoplastic resin having a higher melting point and a sheath materialof the second thermoplastic resin having a lower melting point; a longfiber web in side-by-side structure in which first thermoplastic resinfibers and second thermoplastic resin fibers are aligned in parallel;and a mixed long fiber web in which first thermoplastic resin fibers andsecond thermoplastic resin fibers are mixed together.

Examples of thermoplastic resins used for producing the above-mentionedlong fiber web may be the same as those used for producing the foregoingmonoaxially oriented reticular web such as polyolefin resins includingpolyethylene and polypropylene, polyester resins, polyamide resins, andpolyvinyl alcohol resins.

The composite material used in the second aspect of the invention is theone which is made by laminating crosswise at least one of themonoaxially oriented materials of (a), (b), (c) and (d) at an angle of10° to 80°. In other words, in the composite material, the angle betweenthe direction of orientation and the direction of warp or weft is in therange of 10° to 80°. In addition, it is desirable that the angle betweenthe direction of forming of the flexible elastomer layer and thedirection of warp or weft is also 10° to 80°. More particularly, thelamination is done in such a manner that, if the angle between thedirection of elastomer formation and the direction of warp is 10° to 80°clockwise, the angle between the direction of elastomer formation andthe direction of weft is 10° to 80° counterclockwise.

In the lamination of the monoaxially oriented reticular web of (a), (b)and (c) or the monoaxially oriented tapes are laminated, the thermaladhesion must be done at a temperature above the melting point of thesecond thermoplastic resin but within the range that the lowering ofelasticity of the first thermoplastic resin can be avoided.

In the case of stretched long fiber web (d), it is desirable that thelamination is carried out by using the foregoing conjugated fibershaving the sheath structure or the combined long fiber web composed ofthe long fibers of first thermoplastic resin of higher melting point andthe long fibers of second thermoplastic resin of lower melting point.These fibers may be adhered together with known adhesives ofpolyurethane, vinyl acetate copolymer or else.

The flexible elastomers used in the present invention includethermoplastic elastomers, synthetic rubber and natural rubber.

The above thermoplastic elastomers are exemplified by polyolefins (TPO),polyamides, polystyrenes, polyvinyl chlorides, polyesters, andpolyesters. Among them, thermoplastic polyurethane elastomers arepreferable because of their excellent overall properties in elasticity,durability and economy.

The above thermoplastic polyurethane elastomers are exemplified by thepolymers which are made by reacting organic diisocyanates such astolylenediisocyanate and p,p'-diphenylmethane diisocyanate with lowmelting point polyols such as dihydroxy polyether and dihydroxypolyester in the presence of a chain propagating agent.

The above synthetic rubbers are exemplified by polyurethane rubber,ethylene-propylene rubber, nitrile rubber and isobutylene rubber.

The above ethylene-propylene rubber includes the random copolymer ofmain components of ethylene and propylene (EPM) and the random copolymer(EDPM) which is made by adding a third component of diene monomer suchas dicyclopentadiene or ethylydenenorbornene to the above EPDM.

In the case that the flexible elastomer layers used in the presentinvention are prepared in advance, it is possible to employ variousmethods such as blow film method, T-die method or calender method withextrusion, fluidized dip coating method, and casting method with apolyurethane solution for producing films or sheets, or spun bondedmethod and melt blown method for producing non-woven fabric.

The methods for forming the flexible elastomer on one surface or bothsurfaces of the specific monoaxially oriented material in the presentinvention are exemplified by extrusion lamination, chemical sheeting andthermal bonding.

In the case that polyurethane film prepared by a polyurethane solutioncasting method is used, the obtained cast film is applied with anadhesive agent, preferably an adhesive agent of low polymerizationdegree urethane, and it is laminated with a monoaxially orientedmaterial. After that, the urethane adhesive agent is cured under heatand pressure to obtain the elastic composite material of the presentinvention.

It is desirable that the surface of monoaxially oriented material istreated in the preparation of the elastic composite material of thepresent invention, in order to enhance the adhesive strength. Thesurface treatment includes well known physical surface treatment methodssuch as corona discharge treatment, plasma treatment, and UV radiationtreatment and chemical surface treatment method such as solventtreatment. Among them, the corona discharge treatment is advantageous inview of its effect and cost. The wetting index of the surface of theabove surface-treated material is 40 dyne/cm or higher, preferably above42 dyne/cm, and more preferably above 45 dyne/cm.

The elastic composite material of the present invention may be composedof a monoaxially oriented web and flexible elastomer layer or layers.These materials can be used in combination with other suitablematerials. For example, provided that the monoaxially oriented materialis A, the flexible elastomer layer is B and other material is X, thefollowing combinations of materials are exemplified: A/B, A/B/X, A/X/Band X/A/B.

The above other materials includes spun bonded non-woven fabric and meltblown non-woven fabric made of various resins such as polyethyleneterephthalate (PET), polypropylene (PP), and polyamide (PA); dry-type orwet-type non-woven fabrics made of artificial fibers such as PET, PA andrayon, and natural fibers such as cotton and wool; and other sheetmaterials such as cloth, paper, rubber film and leather.

In the present invention, various known additives can be added to theabove monoaxially oriented material and the flexible elastomer layer solong as the characteristic features of the invention are not impaired.Such additives are exemplified by antistatic agents, anti-foggingagents, organic or inorganic fillers, anti-oxidizing agents, lubricants,organic or inorganic pigments, UV ray absorbers, dispersing agents,nucleating agents, foaming agents, flame retardants, and cross-linkingagents.

The present invention will be described in more detail with reference toexamples. It is to be noted, however, that the scope of the presentinvention should not be limited to these examples.

EXAMPLE 1

In the process as shown in FIG. 2, a longitudinally monoaxially orientedreticular web (a) was prepared through the following procedure.

In a film fabrication step, a multi-layer film of triple-layer structurehaving a thickness ratio of adhesive layer 15 μm/core layer 100μm/adhesive layer 15 μm! and width of 1 m was prepared throughmulti-layer water cooling blown film extrusion method. The firstthermoplastic resin (core layer) was made of high-density polyethylene(density=0.956 g/cm³, MFR=1.0 g/10 min, trademark: Nisseki Staflene E710, made by Nippon Petrochemicals Co., Ltd.) and the secondthermoplastic resin laminated as adhesive layers on both surfaces of thecore layer was made of low-density polyethylene (density=0.924 g/cm³,MFR=3.0 g/10 min, trademark: Nisseki Rexlon F30, made by NipponPetrochemicals Co., Ltd.).

In the next orientation step, it was monoaxially stretched at astretching ratio of 9 to form a monoaxially stretched film of 40 μm inthickness and 30 cm in width. The stretched film was then treated with asplitting device as disclosed in Japanese Utility Model Publication No.Sho 51-38979 to form numerous splits in the film forming direction (MD),thereby preparing a longitudinally monoaxially oriented reticular web(a) of 10 g/m² in unit weight, 11 kg/5 cm in tensile strength and 20% inelongation.

In the next step, both surfaces of the longitudinally monoaxiallyoriented reticular web (a) were subjected to corona discharge treatmentto make the wet tension of the surfaces 45 dyne/cm. Polyurethanethermoplastic elastomer films of 20 μm in thickness were laminated withthe web (a) using an adhesive agent, thereby preparing a controlledelastic composite material having monoaxial elasticity.

The stress at 100% elongation of the obtained monoaxially elasticcomposite material was 100 g/cm.

EXAMPLE 2

Both surfaces of the longitudinally monoaxially oriented reticular web(a) obtained in Example 1 were likewise applied with films ofethylene-propylene random copolymer rubber film of 20 μm in thicknessusing an adhesive agent to obtain a monoaxially elastic compositematerial.

The stress at 100% elongation of the obtained monoaxially elasticcomposite material was 160 g/cm.

EXAMPLE 3

Both surfaces of the longitudinally monoaxially oriented reticular web(a) obtained in Example 1 were applied likewise with polyurethane spunbonded non-woven fabric of 25 g/m² in unit weight and 0.12 mm inthickness (trademark: Espunsione UH 025, made by Kanebo, Ltd.) using anadhesive agent to obtain a monoaxially elastic composite material.

The stress at 100% elongation of the obtained monoaxially elasticcomposite material was 80 g/cm and the recovery ratio after 100%elongation was 90%.

EXAMPLE 4

Both surfaces of the longitudinally monoaxially oriented reticular web(a) obtained in Example 1 were applied likewise with polyurethane meltblown non-woven fabric of 20 g/m² in unit weight and 0.10 mm inthickness using an adhesive agent to obtain a monoaxially elasticcomposite material.

The stress at 100% elongation of the obtained monoaxially elasticcomposite material was 60 g/cm and the recovery ratio after 100%elongation was 85%.

EXAMPLE 5

In a film fabrication step, a multi-layer film of triple-layer structurehaving a thickness ratio of adhesive layer 15 μm/core layer 100μm/adhesive layer 15 μm! and width of 90 cm was prepared throughmulti-layer water cooling blown film extrusion method. The firstthermoplastic resin (core layer) was high-density polyethylene(density=0.956 g/cm³, MFR=1.0 g/10 min, trademark: Nisseki Staflene E710, made by Nippon Petrochemicals Co., Ltd.) and the secondthermoplastic resin laminated as adhesive layers on both surfaces of thecore layer was low-density polyethylene (density=0.924 g/cm³, MFR=3.0g/10 min, trademark: Nisseki Rexlon F 30, made by Nippon PetrochemicalsCo., Ltd.).

In the next orientation step, multi-layer film was monoaxially stretchedat a stretching ratio of 9 to prepare a monoaxially stretched film of 40μm in thickness and 30 cm in width. The stretched film was then treatedwith a splitting device as disclosed in Japanese Utility ModelPublication No. Sho 51-38979 to form numerous splits in the longitudinaldirection (MD), and the width of the obtained split film was spreadthree times transversally, thereby preparing a longitudinallymonoaxially oriented reticular film (a). A pair of the obtainedreticular films were laminated crosswise at an angle of 60° oforientation axes to prepare a composite material A.

In the next step, both surfaces of the composite material A weresubjected to corona discharge treatment and polyurethane thermoplasticelastomer of 20 μm in thickness was formed by extrusion laminationmethod on both surfaces of the composite material A. In the extrusionlamination, the direction of warp of the composite material A wasinclined by 30° clockwise to the direction of elastomer formation andthe direction of weft of the composite material A was inclined by 30°counterclockwise to the direction of elastomer formation to obtain aelastic composite material.

The ratio of elongation of the obtained elastic composite material in MDwas 15% and in TD, 50%.

EXAMPLE 6

A multi-layer film was prepared in the like manner as in the process inFIG. 4 and the multi-layer film was stretched transversally (TD) in theorientation step to obtain a transversally monoaxially orientedreticular web (b). This web (b) was crosswise laminated with thelongitudinally monoaxially oriented reticular web (a) such that the axesof orientation of both the webs intersected at an angle of 60° to obtaina composite material B.

In the next step, both surfaces of the composite material B were appliedwith 20 μm thick polyurethane thermoplastic elastomer by extrusionlamination method in the like manner as in Example 5. In the extrusionlamination, the direction of warp of the composite material B wasinclined by 60° clockwise to the direction of the formation of elastomerand the direction of weft of the composite material A was inclined by60° counterclockwise to the direction of elastomer formation to obtain aelastic composite material.

The ratio of elongation of the obtained elastic composite material in MDwas 50% and in TD, 15%.

EXAMPLE 7

Experiment was carried out in the like manner as in Example 5 exceptthat the longitudinally monoaxially stretched film was cut intomonoaxially oriented tapes (c) and two groups of the tapes werelaminated crosswise with an intersecting angle of orientation axes of60° to obtain a monoaxially oriented non-woven fabric.

The ratio of elongation of the obtained elastic composite material in MDwas 15% and in TD, 50%.

EXAMPLE 8

Experiment was carried out in the like manner as in Example 5 exceptthat the longitudinally monoaxially stretched film was cut intomonoaxially oriented tapes (c) and two groups of the tapes were wovencrosswise with an intersecting angle of orientation axes of 60° toobtain a monoaxially oriented woven fabric.

The ratio of elongation of the obtained elastic composite material in MDwas 15% and in TD, 50%.

In the following, the use examples of the stretched long fiber web (d)of the present invention are shown.

Evaluation of properties were done in accordance with the followingmethods:

(1) Tensile Strength

Tested according to JIS L 1096 and test pieces of 1 cm in width wereused.

(2) Drape Property

Tested according to JIS L 1086, cantilever method.

Five (5) test pieces of 15 cm in length and 2 cm in width were preparedfrom stretched long fiber web, in which the direction of fibers arealigned with the long sides of test pieces. The scale was read when atest piece came into contact with the inclined plane of cantilever. Ifthe obtained value was small, the test piece was regarded as flexibleand good in drape property.

(3) Feeling

According to the following standard, the samples for feeling test wasevaluated by 5 monitors who were voluntarily selected.

⊕: Determined as good by 4 or more monitors

O: Determined as good by 3 monitors

×: Determined as good by 2 or less monitors

EXAMPLE 9

In the first place, a stretched long fiber web was prepared according tothe process disclosed in Japanese Patent Publication No. Hei 3-36948.

Filaments were prepared by spinning polypropylene (trademark: NissekiPolypro J 120, made by Nippon Petrochemicals Co., Ltd.) and the obtainedfilaments were aligned transversally on a running conveyor belt with hotcircularly moving air to obtain a long fiber web of spun filaments of 2denier in fineness. With pulley-type transversally stretching method asdisclosed in Japanese Laid-Open Patent Publication No. Sho 57-41922, thelong fiber web was stretched by 10 times in transversal direction so asto make the fineness 0.2 denier and transversally stretched long fiberweb of 8 g/m² in unit weight was prepared by means of temporary adhesionwith polyvinyl alcohol.

In the next step, both surfaces of the stretched long fiber web weresubjected to corona discharge treatment and polyurethane thermoplasticelastomer films of 20 μm in thickness were applied to the surfaces usingan adhesive to obtain a monoaxially controlled elastic compositematerial.

The stress at 100% longitudinal elongation of the obtained elasticcomposite material was 100 g/cm and the maximum stress in transversaldirection was 1000 g/cm, at which the maximum elongation was 7%. Theseresults are shown in the following Table 1 together with the testresults of drape property and feeling.

EXAMPLE 10

Both surfaces of the transversally stretched long fiber web obtained inExample 9 were subjected to corona discharge treatment and films ofethylene-propylene random copolymer rubber of 20 μm in thickness werelaminated with an adhesive to obtain a monoaxially controlled elasticcomposite material.

The stress at 100% longitudinal elongation of the obtained compositematerial was 160 g/cm and the maximum stress in transversal directionwas 1000 g/cm, at which the maximum elongation was 7%. These results areshown in the following Table 1.

EXAMPLE 11

Both surfaces of the transversally stretched long fiber web obtained inExample 9 were subjected to corona discharge treatment and polyurethanespun bonded non-woven fabric (trademark: Espunsione UH 025, made byKanebo, Ltd.) of 25 g/m² in unit weight and 0.12 mm in thickness waslaminated with an adhesive to obtain a monoaxially controlled compositematerial.

The stress at 100% longitudinal elongation of the obtained compositematerial was 80 g/cm and the maximum stress in transversal direction was1000 g/cm, at which the maximum elongation was 7%. These results areshown in the following Table 1.

EXAMPLE 12

Both surfaces of the transversally stretched long fiber web obtained inExample 9 were subjected to corona discharge treatment and polyurethanemelt blown non-woven fabric of 20 g/m² in unit weight and 0.10 mm inthickness was laminated with an adhesive to obtain a monoaxiallycontrolled composite material.

The stress at 100% longitudinal elongation of the obtained compositematerial was 60 g/cm and the maximum stress in transversal direction was1000 g/cm, at which the maximum elongation was 7%. These results areshown in the following Table 1.

COMPARATIVE EXAMPLE 1

The polyurethane spun bonded non-woven fabric (trademark: Espunsione UH025, made by Kanebo, Ltd.) of 25 g/m² in unit weight and 0.12 mm inthickness as used in Example 11 was subjected to the similar measurementas above.

The stress at 100% longitudinal elongation was 80 g/cm and the stress at100% transversal elongation was 40 g/cm, which results are shown in thefollowing Table 1.

                  TABLE 1                                                         ______________________________________                                        Items     Ex. 9   Ex. 10  Ex. 11                                                                              Ex. 12                                                                              Comp. Ex. 1                             ______________________________________                                        Longitudinal                                                                  Direction                                                                     Stress at 100%                                                                          100     160     80    60    80                                      Elongation                                                                    (g/cm)                                                                        Transversal                                                                   Direction                                                                     Max. Stress                                                                             1000    1000    1000  1000  40(*)                                   (g/cm)                                                                        Max. Elongation                                                                         7       7       7     7     --                                      (%)                                                                           Drape Property                                                                          2       2       1     1     2                                       (cm)                                                                          Feeling   O       O       ⊕ ⊕ ⊕                                   ______________________________________                                         Note: (*) The stress at 100% elongation                                  

The controlled flexible elastic composite material according to thepresent invention have good controlled elasticity because both surfacesof a specific monoaxially oriented material are applied with flexibleelastomer layers. Furthermore, by laminating at least two layers ofspecific stretched long fiber web and flexible elastomer layer, thelaminate can have good feeling and proper elasticity. In addition, it isnot elastic in its perpendicular direction and these controlled elasticcomposite materials have good mechanical strength.

With making the best use of the above characteristic features, thecomposite material of the present invention can be used widely forproducing the fixing materials for the waist parts of the disposablediapers, clothes for working and surgical operation, caps for foodworks, garbage collecting and IC manufacturing process, fixings forgloves and shoe covers, and fixings for adhesive plasters and bandages.

What is claimed is:
 1. A controlled elastic composite materialcomprising a flexible elastomeric layer and a first oriented layer, saidfirst oriented layer formed of a thermoplastic resin selected from thegroup consisting of (a) a longitudinally monoaxially oriented reticularfilm; (b) a transversely monoaxially oriented reticular film; and (c) aplurality of monoaxially stretched or rolled tapes disposed in parallel.2. A material in accordance with claim 1 comprising a second orientedlayer formed of a thermoplastic material selected from the groupconsisting of (a), (b) and (c) wherein said first and said secondoriented layers are disposed at an angle of from 10° to 80° relative toeach other.
 3. A material in accordance with claim 1 wherein said firstoriented layer is a multilayered film formed by laminating a secondthermoplastic resin layer on one or both surfaces of a firstthermoplastic resin layer with the proviso that the melting point ofsaid second thermoplastic resin is lower than that of said firstthermoplastic resin.
 4. A material in accordance with claim 1 whereinthe ratio of orientation of said first oriented layer is in the range of1.1 to
 15. 5. A material in accordance with claim 2 wherein said secondoriented layer is (c) and wherein said plurality of tapes are a pair ofwoven or non-woven fabrics.
 6. A controlled elastic composite materialcomprising a flexible elastomeric layer and an oriented layer, saidoriented layer comprising a first and a second oriented materialcrosswise laminated with each other at an intersecting angle of between10° and 80°, said first and said second oriented materials being thesame or different and selected from the group consisting of (a) alongitudinally monoaxially oriented reticular web; (b) a transverselymonoaxially oriented reticular web; (c) a plurality of monoaxiallystretched or rolled tapes which are disposed in parallel; and (d) a webwhich includes a plurality of fibers aligned in one direction and thenstretched or rolled in that direction.
 7. A material in accordance withclaim 6 wherein said oriented layer is (c) and wherein said plurality ofmonoaxially stretched or rolled tapes disposed in parallel is a pair ofwoven or non-woven fabric webs.
 8. A material in accordance with claim 6wherein said monoaxially oriented material is selected from the groupconsisting of (a), (b) and (c) and wherein said materials are made froma multilayered film formed by laminating a second thermoplastic resinlayer on one or both surfaces of a first thermoplastic resin layer withthe proviso that the melting point of said second thermoplastic resin islower than that of first thermoplastic resin.
 9. A material inaccordance with claim 6 wherein the ratio of orientation of saidmonoaxially oriented material is in the range of between 1.1 and 15 andwherein said monoaxially oriented material is selected from the groupconsisting of (a), (b) and (c).
 10. A material in accordance with claim6 wherein said monoaxially oriented material is (d) and wherein theratio of stretching or rolling of said long fibers is in the range ofbetween 5 and 20 and the fineness of said fibers is in the range ofbetween 0.01 and 10 denier.
 11. A material in accordance with claim 6wherein said monoaxial material is (d) and wherein said fibers arecomposed of conjugate fiber consisting of a high melting point materialand a low melting point material.
 12. A controlled elastic compositematerial comprising a flexible elastomer layer and an oriented layer,said oriented layer including at least one monoaxially oriented fiberweb having a plurality of fibers aligned in one direction and stretchedor rolled in said direction.
 13. A material in accordance with claim 12wherein said oriented layer is formed by crosswise laminating a pair ofmonoaxially oriented fiber webs at an intersecting angle of between 10°and 80°.
 14. A material in accordance with claim 12 wherein the ratio ofstretching of said monoaxially oriented long fiber web is in the rangeof between 5 and 20 to produce a fineness in the range of between 0.01and 10 denier.
 15. A material in accordance with claim 12 wherein saidmonoaxially oriented fiber web is composed of conjugate fibersconsisting of a high melting point material and a low melting pointmaterial.